The present invention relates to a refractory shutoff assembly or unit for controlling the discharge of molten metal from a metallurgical vessel. Particularly, the present invention relates to such an assembly including a refractory stator and a refractory rotor. The present invention also relates to such refractory stator and such refractory rotor individually. . The stator is adapted to be mounted in the wall of a metallurgical vessel, and the rotor is positioned generally within the interior of the vessel and is guided for movement relative to the stator by the stator. At least one transverse opening and at least one axial opening in the assembly can be brought into and out of alignment by rotating and/or axially moving the rotor relative to the stator, thereby achieving relative opening and closing of the shutoff assembly.
Such a shutoff assembly is suitable particularly for metallurgical vessels employed in continuous casting systems wherein molten metal is poured or discharged from a metallurgical vessel in a controlled manner into a continuous casting mold. The shutoff assembly is controlled in such a manner by means of a control process that the quantity of molten metal discharged from the metallurgical vessel maintains a constant filling height in the mold. Higher requirements for accurately metered pouring or discharge from the metallurgical vessel are imposed on the shutoff assembly that serves as a control element of such discharge.
German DE-OS 37 31 600 discloses a stator mounted in a vessel wall and a rotor guided in the stator within the vessel, wherein the rotor can be rotated and also moved longitudinally or axially by a drive arranged above the vessel. Transverse inlet openings in the walls of the stator or rotor and a longitudinal opening originating from such openings in the stator make it possible to pour or discharge molten metal when such openings overlap. Under normal operating conditions, relatively low torsion, tension or other forces act on the rotor or stator, such elements of course being formed of a refractory ceramic material. However, in the event that some molten metal infiltrates between the stator and rotor and then solidifies, such can cause the rotor to jam with respect to the stator, whereby interruption of discharge of the molten metal is prevented. Also, such jamming can cause parts of the stator or rotor to break, thereby also preventing shutoff of the assembly.